International Lunar Resources Exploration Concept (1993)

Image: NASA

By the end of 1992, the handwriting had been on the wall for the Space Exploration Initiative (SEI) for some time. President George H. W. Bush had launched his moon and Mars exploration initiative on the 20th anniversary of the Apollo 11 lunar landing (20 July 1989), but it had almost immediately run headlong into a minefield of fiscal and political difficulties. The change of Presidential Administration in January 1993 was the final nail in SEI’s coffin. Nevertheless, exploration planners across NASA continued to work toward SEI goals until early 1994.

In February 1993, Kent Joosten, an engineer in the Exploration Program Office (ExPO) at NASA’s Johnson Space Center (JSC) in Houston, Texas, proposed a plan for lunar exploration which, he hoped, would take into account the emerging realities of post-Cold War space exploration. His International Lunar Resources Exploration Concept would, he wrote, reduce “development and recurring costs of human exploration beyond low-Earth orbit” and “enable lunar surface exploration capabilities significantly exceeding those of Apollo.” It would do these things by exploiting the abundant oxygen in lunar regolith (that is, surface material) as oxidizer for burning liquid hydrogen fuel brought from Earth, shipping most cargo to the moon separately from crews, employing teleoperations, and relying on cooperation with the Russian Federation.

Joosten’s concept was a variant of the Lunar Surface Rendezvous (LSR) mission mode. The Jet Propulsion Laboratory (JPL) in Pasadena, California, put forward LSR in 1961 as a candidate mode for achieving President John F. Kennedy’s goal of a man on the moon by the end of the 1970s. In 1962, after NASA selected Lunar Orbit Rendezvous (LOR) as its Apollo lunar mission mode, JPL’s LSR scheme faded into obscurity. Joosten’s concept was not inspired by the early 1960s scenario; instead, his work drew upon contemporary In-Situ Resource Utilization (ISRU) and Mars surface rendezvous techniques employed in NASA’s Mars Design Reference Mission 1.0 and Martin Marietta’s Mars Direct scenario.

The Apollo LOR mode was designed to permit the U.S. to reach the moon quickly and relatively cheaply, not to support a sustained lunar presence. It split lunar mission functions between two piloted spacecraft, each of which comprised two modules. Modules were discarded after they fulfilled their functions.

Joosten’s single moonship would be roughly intermediate in size between the Apollo LM (left) and the Apollo CSM (right). Image: NASA

At the start of an Apollo lunar mission, a Saturn V rocket launched a Command and Service Module (CSM) mothership and a Lunar Module (LM) moon lander into Earth orbit, then the rocket’s S-IVB third stage reignited to push them out of Earth orbit toward the moon. This maneuver, called trans-lunar injection (TLI), marked the real start of the lunar voyage. After TLI, the CSM and LM separated from the spent S-IVB.

As they neared the moon, the crew fired the CSM engine to slow down so that the moon’s gravity could capture the Apollo spacecraft into lunar orbit. The LM then separated from the CSM and descended to the lunar surface using the engine in its Descent Stage. After a maximum of three days on the moon, the Apollo lunar crew lifted off in the LM Ascent Stage using the Descent Stage as a launch pad. The astronaut in the CSM rendezvoused and docked with the Ascent Stage to recover the moonwalkers – hence the name Lunar Orbit Rendezvous – then the crew discarded the Ascent Stage and fired the CSM engine to depart lunar orbit for Earth. Nearing Earth, they cast off the CSM’s Service Module and reentered Earth’s atmosphere in its conical Command Module (CM).

According to Joosten, a spacecraft that flew from Earth to the lunar surface, arrived on the moon with empty oxidizer tanks, and reloaded them for the trip home with liquid oxygen mined and refined from lunar regolith, could have about half the TLI mass of equivalent LOR spacecraft. The Apollo 11 CSM, LM, and spent S-IVB stage had a combined mass at TLI of about 63 metric tons; the International Lunar Resources Exploration Concept spacecraft and its spent TLI stage would have a mass of about 34 metric tons. This substantial mass reduction would permit use of a launch vehicle smaller than the Apollo Saturn V, potentially slashing lunar mission cost.

Lunar regolith is on average about 45% oxygen by mass. According to Joosten, literally dozens of lunar oxygen extraction techniques are known. He listed 14 as examples, including one, Hydrogen Ilmenite Reduction, for which the U.S. Patent Office had issued a patent to the U.S./Japanese Carbotek/Shimizu consortium. He assumed a lunar oxygen extraction process involving “solid-state high-temperature electrolysis” which would produce 24 metric tons of liquid oxygen per year.

Joosten estimated that this process would need between 40 and 80 kilowatts of continuous electricity, and suggested that a nuclear reactor would be the best power-supply option. Such a reactor would have ample reserve power for charging electrically powered teleoperated mining vehicles and could supply crew electricity needs when astronauts were present.

One-way automated cargo landers, each rectangular in shape and capable of delivering 11 metric tons of payload to the moon’s surface, would be assembled and packed in the U.S. and shipped to Russia in C-5 Galaxy or Antonov-124/225 transport planes, then launched on Russian Energia rockets from Baikonur Cosmodrome in Kazakstan. Joosten noted that Energia had flown twice before the fall of the Soviet Union: in 1987 with a side-mounted payload (the large Polyus module) and in 1988 bearing an automated Buran shuttle orbiter.

Based on Russian data provided to NASA, launch teams at Baikonur could service two Energia rockets simultaneously. Three Energia launch pads existed to launch lunar cargoes. Energia could place a 5.5-meter-diameter canister containing a cargo lander into Earth orbit attached to a Russian “Block 14C40″ upper stage. The upper stage would then perform the TLI burn, boosting the cargo lander toward the moon.

Shuttle-derived heavy-lift boosters would launch Joosten’s piloted landers from the twin Kennedy Space Center (KSC) Complex 39 Space Shuttle pads. The pads, monolithic Vehicle Assembly Building, and other KSC facilities would require modifications to support the new piloted lunar program, but no wholly new facilities would need to be constructed, Joosten wrote.

Joosten considered both Shuttle-C and in-line Shuttle-derived launchers. The Shuttle-C design had a cargo module with attached Space Shuttle Main Engines (SSMEs) mounted on the side of the Shuttle External Tank (ET) in place of the delta-winged Shuttle Orbiter. The in-line design, a conceptual ancestor of the Space Launch System currently under development, placed a cargo module on top of a modified ET and three SSMEs underneath. The tank would have attached to its sides twin Advanced Solid Rocket Motors more powerful than their Space Shuttle counterparts.

The Shuttle-derived heavy-lift rocket would launch the piloted lander, bearing an international crew and about two tons of cargo, into Earth orbit. About 4.5 hours after liftoff, following a systems checkout period, the TLI stage would place the piloted lander on a direct trajectory to land near the pre-established automated oxygen production facilities.

Russia would pay for Energia and the Block 14C40 stage, while NASA would pay for the Shuttle-derived rocket and TLI stage, crew and cargo landers, lunar surface payloads such as moonbus rovers and teleoperated carts, and lunar oxygen production systems. In exchange for its participation, Russian cosmonauts could fly to the moon. If, however, U.S./Russia space cooperation was for any reason curtailed, NASA could continue the moon program by taking over the cargo launches – provided, of course, that U.S. policy-makers judged the more costly all-U.S. moon program to be worthwhile.

Launch of piloted lunar lander and translunar injection rocket stage on a Shuttle-C launcher. The side-mounted aerodynamic shroud covering the lander and stage is shown as partially transparent; in reality, it would, of course, be opaque white, with only the conical crew capsule at the top visible. Image: NASAShortly after a piloted lander sets down on the moon, a teleoperated oxygen cart (left) rolls up to automatically refill its tanks. Image: NASA

Joosten’s crew lander design outwardly resembled the fictional “Eagle” transport spacecraft from the 1970s Gerry Anderson TV series Space: 1999. The crew compartment, a conical capsule modeled on the Apollo Command Module (but lacking a nose-mounted docking unit), would be mounted on the front of a horizontal, three-legged lander. At launch, the capsule would sit on top of the crew lander surmounted by a solid-propellant launch escape system tower. The three landing legs would fold against the lander’s belly beneath a streamlined shroud during ascent through Earth’s lower atmosphere.

On the moon, the crew hatch would face downward, providing ready access to the surface via a ladder on the lander’s single forward leg; on the launch pad, the hatch would permit horizontal access to the capsule interior much as did the Apollo CM hatch. The crew compartment windows would be inset into the hull and oriented to enable the pilot to view the landing site during descent.

The crew spacecraft would land on and launch from the moon using four belly-mounted throttleable rocket engines. During descent to the lunar surface, the engines would burn Earth oxygen and hydrogen. Soon after lunar touchdown, the lander would be reloaded with liquid oxygen from the automated lunar oxygen plant. For flight back to Earth, the entire crew lander would lift off from the moon, so no expendable descent stages would be left behind to clutter up the site. After a brief period in lunar parking orbit, the lander would ignite its four engines again to place itself on course for Earth. During return to Earth, Joosten’s spacecraft would burn Earth hydrogen and lunar oxygen.

Nearing Earth, the crew capsule would separate from the lander section and orient itself for reentry by turning its Apollo-style bowl-shaped heat shield toward the atmosphere. The lander section, meanwhile, would steer toward a reentry point well away from populated areas, though most of it would burn up during reentry. The crew capsule would deploy a steerable parasail-type parachute. Joosten recommended that NASA recover the capsule on land – perhaps at Kennedy Space Center – to avoid the greater cost of an Apollo-style CM splashdown and water recovery.

Robotic exploration missions would precede the new piloted lunar program. These would have “science linkages,” Joosten noted, but would serve mainly to prepare the way for lunar oxygen production and safe piloted landings. Robotic orbiters might be flown as part of JSC’s proposed Lunar Scout program; landers might employ JSC’s proposed Artemis Common Lunar Lander design. In addition to locating oxygen-rich regolith and performing ISRU experiments under real lunar conditions using real lunar materials, the robot explorers would map candidate landing sites and certify site safety.

Joosten acknowledged that the International Lunar Resources Exploration Concept emphasized technologies “in somewhat different areas than most exploration scenarios.” Among these were teleoperated surface vehicles and surface mining and processing. On the other hand, the technological areas it emphasized had a “high degree of terrestrial relevance,” a fact which, he argued, might provide a selling point for the new piloted lunar program.

Joosten envisioned a three-phase piloted lunar program, though he provided details only for Phases 1 and 2. In Phase 1, three cargo landers would deliver equipment to the target landing site ahead of the first piloted mission; the Russians would thus conduct the first three missions of the program.

Flight 1 of Phase 1 would deliver the nuclear reactor on a teleoperated “cart” and the automated liquid oxygen production facility (the latter would remain attached to its lander); flight 2 would deliver teleoperated diggers, regolith haulers, oxygen tankers, and carts for auxiliary fuel-cell power and consumables resupply; and flight 3 would deliver a pressurized moonbus exploration rover and science equipment for the astronauts who would reach the moon on flight 4.

The first piloted lander carrying two astronauts would then arrive for a two-week stay. The crew would inspect the automated mining and oxygen production systems and explore using the moonbus rover. In Phase 1, the moonbus would be capable of traveling away from the crew lander landing site for two or three days at a time. Several Phase 1 piloted missions to the site would be possible; alternately, NASA and Russia could skip immediately to Phase 2 after a single Phase 1 piloted flight.

In Phase 2, three more cargo flights would deliver to the same site a second moonbus rover, a support module with attached airlock derived from Space Station hardware designs, consumables in a cart-mounted pressurizable Space Station-derived module, and science equipment. A piloted flight would then deliver a four-person crew for a six-week lunar surface stay. The crew would divide up into pairs, with each pair living in and operating a moonbus rover. The support module/airlock would include docking units so that the two moonbuses and the consumables module cart could link to it, forming a small outpost.

The moonbuses would tow auxiliary power carts in Phase 2 to enable longer traverses across the lunar surface. The moonbus/cart combinations might travel in pairs along parallel routes or one moonbus might remain at the outpost while the other moonbus and its power cart ventured far afield. In the event that a moonbus rover failed beyond walking distance from the outpost and could not be repaired, the other moonbus could rescue its crew.

Phase 3 might see larger crews; alternately, NASA (perhaps still partnering with Russia) might change direction and use technology developed during the lunar program to put humans on Mars. Joosten identified the piloted moon lander crew capsule, Shuttle-derived heavy-lift rocket, moonbus rovers, and Energia as candidate Mars mission hardware. Both Energia and the Shuttle-derived rocket might be upgraded for piloted Mars missions; they might even be combined to create an international heavy-lift rocket more powerful than either Energia or the Shuttle derivative.

Two views of the Phase 2 lunar outpost. The lower view is turned 90 degrees clockwise relative to the upper view.